•i 94 Dr. Wollaston on Platina, &c. 
of this ingredient, and occasion a presumption that osmium 
and rhodium may hereafter appear, when we can obtain this 
mineral in larger quantity. 
Since the whole weight of metal employed in the last ex- 
periment did not exceed iy 5 grain, it is in vain to attempt to 
estimate the proportion of the ingredients, but if I am near 
the truth, in considering the quantity of the red precipitate as 
about one fifth of a grain, of which less than half is platina, 
those who are best acquainted with the intense colouring 
power of iridium may endeavour to form a conception of the 
extremely small quantity that can be present. 
As soon as I had ascertained the existence of native palla- 
dium, I endeavoured, by examination of its external characters, 
to distinguish its appearance from that of the surrounding 
substances, and I found it by no means difficult, although no 
difference of colour could be discerned. Having remarked 
that the larger fragment appeared rather fibrous, and that 
the fibres were in some degree divergent from one extremity, 
I examined the remainder of the small specimen which had 
originally been given to me, and by this peculiarity of struc- 
ture I soon detected a third fragment, which upon trial proved 
to be the same substance. By favour of the Chev. de Souza 
I was also permitted, with this view, to examine the specimen 
which remained in his possession, and had soon the satisfac- 
tion of discovering two more fragments of the same mineral, 
and as I was in no one instance deceived in my choice, by 
attending to the radiating fibres, I am in hopes that this ex- 
ternal character will enable persons to distinguish that metal, 
in situations where they have not an opportunity of deciding 
by chemical experiment. 
